The long-term goal of this project is to acquire a more complete understanding of the relationship of structure to function in pituitary growth hormone (GH). Peptides will be derived from human GH by various enzymatic and chemical means. Then attempts will be made to recombine these fragments noncovalently. The recombinant molecules will then be tested in a variety of bioassays that test for the anabolic, insulin-like diabetogenic and lactogenic activities of GH and in radioimmunological and radioreceptor assays. An effort will also be made to produce hybrid recombinant molecules by combining fragments of human GH with fragments of porcine GH, in order to gain some insight into the structural basis for the species specificity and lactogenic activity of human GH.